NEW YORK, NEW YORK—A voluntary moratorium on potentially dangerous experiments aimed at understanding highly virulent strains of the H5N1 influenza virus should continue for the time being, National Institute of Allergy and Infectious Diseases (NIAID) Director Anthony Fauci told a meeting of flu scientists here. But, he added, scientists should redouble their efforts to engage with the larger public to gain support for the vital but risky work.

"The flu scientific community can no longer be the only player in the discussion about this research," Fauci said. "You will unquestionably lose the battle for public support for your research if you ignore this issue." Fauci remarks, delivered at the annual meeting of the NIAID's influenza research centers of excellence, also echoed a call for openness and transparency he made in June in the pages of Science, published by AAAS, which also publishes ScienceInsider.

The moratorium, announced by 39 scientists this past January, came amidst controversy over publishing two studies that described how researchers made H5N1 more transmissible between mammals—possibly setting the stage for a flu pandemic. After a lengthy review, the U.S. National Science Advisory Board for Biosecurity (NSABB) ultimately recommended that the U.S. government allow full publication of both studies. One, by a team led by Yoshihiro Kawaoka—who has a joint appointment at the University of Tokyo and the University of Wisconsin, Madison—was published by Nature. The other, from a team led by Ron Fouchier of Erasmus MC in Rotterdam, the Netherlands, was published by Science.

What to do about the moratorium, however, has been the subject of controversy. It was originally supposed to last just 60 days, but it was later extended indefinitely. In April, Fauci -- who is not a signatory to the moratorium but leads a major flu research funding agency and encouraged scientists to adopt the pause in a bid to calm public fears—told a U.S. Senate committee that the moratorium should continue pending further discussion. In June, he said the research community still had "a lot of homework to do … and some boxes to check" before the moratorium could be lifted, including agreeing on what types of flu research were worth the risks.

In today's remarks, Fauci highlighted one particularly sensitive research area: so-called "gain-of-function" experiments that allow scientists to create and study flu viruses that are more pathogenic than those found in nature. A key argument for doing such experiments, he noted, is that they allow scientists to understand how a virus might evolve in the future.

"There is a real and present danger of the natural evolution of the virus and that is why you do the experiments that might appear to be risky in the eyes of some," he said. "You do the experiments so we can stay ahead of the naturally evolving risk."

Many critics, however, have questioned whether such experiments are really useful, and whether scientists can safely contain potentially dangerous new pathogens. "The world sees it differently," Fauci said, "and they ask the question, … namely: Should these experiments should have been performed and/or published in the first place?"

Scientists, he said, often "answer that the benefit outweighs the risk. … However, it is essential we respect the concern of the public domestically or globally, and not ask them to take the word of the influenza scientist."

Along with concerns about bioterrorists using published papers to guide deliberate efforts to stoke a pandemic, Fauci said he worried about "unregulated" laboratories, perhaps outside of the United States, doing work "sloppily" and leading to an inadvertent pandemic."Accidental release is what the world is really worried about," he said.

To address such concerns, Fauci counseled more dialogue and patience. Before lifting the moratorium, scientists need to take more time to share information with the public and discuss the tradeoffs inherent in influenza research, he said, perhaps through international workshops and meetings.

Not taking such steps, he said, would be counterproductive. "If we, without having this broader input, say, 'Let's lift the moratorium,' the consequences of that would make it more difficult to get back on the track of doing this research," he said.

Fauci also suggested that there are plenty of potentially important H5N1 experiments that aren't covered by the moratorium. Allowable experiments, for instance, could test the assumption that an influenza virus infecting a small mammal such as a ferret could also infect a monkey. Or, he said, researchers could start more studies to answer questions about how the immune system responds to the virus.

"The game has changed for pandemic flu scientists and the agencies that support them," he said.NIAID, the National Institutes of Health, and the Department of Health and Human Services "cannot recommend or go along with the lifting of the moratorium … as long as the questions that I have just mentioned and brought up remained unanswered."

That stance got a predictably mixed review from members of the audience, which included both supporters and opponents of lifting the moratorium. But several scientists publicly thanked the NIAID director for his frank comments. "I think [Fauci] articulated the case for continuing the moratorium today better than the case for continuing the moratorium had been articulated previously, and that's important," virologist Nancy Cox of the Centers for Disease Control in Atlanta told ScienceInsider after Fauci's session. She was among the original moratorium signers. During the session, she also said that "there needs to be a better explanation of what kinds of work on H5N1 can continue under the moratorium and what can't."

Fouchier, for one, told Fauci that it was time for the moratorium to end. "I think we have done what we can do about accidental release," he said. "Accidental release outside of U.S. cannot be addressed by regulation," he noted, adding that some of the signers of the moratorium don't receive U.S. funds. He also pointed out that labs around the world already have dangerous pathogens on hand, including hundreds with samples of the 1957 H2N2 pandemic virus. "If that virus [gets released] it will kill 1 to 2 million people," he said, suggesting that the infectious disease community has shown it can work with dangerous pathogens responsibly.

Fauci's response to Fouchier: Share that argument with the public. What Fouchier said "doesn't get the transparent airing it deserves," Fauci said. "That argument you made has to be made in a forum that people can understand what you are saying."

By the end of the hour-long session, it appeared that researchers were no closer to resolving when—or if—the moratorium should end. "If there is disagreement among the people in this room, how is a decision going to be taken?" asked virologist Adolfo García Sastre of the Mt. Sinai School of Medicine in New York City.

Fauci said that the detailed guidelines it is developing for universities and other institutions to conduct potentially risky dual use research of concern (DURC) will help spell out an answer. As part of his talk, he shared the U.S. government's progress on the DURC guidelines, which have been shaped by a new, yet-to-be-named interagency committee that includes National Institutes of Health officials. The group has been meeting to craft the rules and Fauci expects them to be released "reasonably soon." Upon their release, Fauci says he hopes they will be subject to public comment and receive input from an international consultative conference. The guidelines now cover 15 pathogens and "likely will be modified in the future to include more than the 15." In the past, Fauci has said the release of the guidelines would be necessary before he would support lifting the H5N1 research moratorium.